Field of the Invention
The invention relates to a device for aligning sheets in a feeder of a sheet-processing machine, especially a printing press.
In order to achieve good feed register with thin printing materials (lightweight grammages), it is necessary to hold down the leading edge of the respective sheet in the vicinity of the front lays. For that purpose, top lays are provided which, in order to be able to fulfill the aforementioned objective, must be adaptable, by vertical adjustment, to the varying grammages of the sheets to be processed. Otherwise, in particular for lightweight grammages, register problems may occur, for example so-called ghosting.
A device of the type referred to in the introduction hereto has been disclosed in German Patent DE 196 00 793 C2, corresponding to U.S. Pat. No. 5,761,998. In that heretofore-known construction, separate front lays and separate top lays are provided, which are respectively pivotable and vertically adjustable, independently of one another. The gear mechanisms or transmissions required for that purpose are accordingly complicated, and therefore expensive.
It is accordingly an object of the invention to provide a device for aligning sheets on a feeder of a sheet-processing machine, especially a printing press, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and in which, with a tolerable technical and financial expenditure, the feed register is optimized, especially for the purpose of avoiding undesired, feeder-induced ghosting with lightweight grammages.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for aligning sheets on a feeder of a sheet-processing machine. The device includes a plurality of pivotably disposed front lays and a plurality of pivotably disposed top lays. The top lays are vertically adjustable. The respective front lays and the respective top lays are assigned to and combined with one another and have a common pivoting drive, a push rod for vertically adjusting the top lays, and a wedge-like slide for actuating the push rod.
In accordance with another feature of the invention, the push rod extends at least approximately vertically and through an upper end thereof engages via a screw connection with the top lays. The push rod, through a lower end thereof, is operatively connected via a sliding piece to a wedge-like slide for at least approximately horizontally displacing the slide.
In accordance with a further feature of the invention, the lower end of the push rod is anchored in a recess formed in the sliding piece, for firmly connecting the push rod to the sliding piece.
In accordance with an added feature of the invention, the sheet-aligning device further includes a motor-actuatable spindle drive. The wedge-like slide is connected to the spindle drive via an at least approximately horizontally extending rod drive.
In accordance with an additional feature of the invention, the spindle drive includes a spindle rotatively actuatable by a motor and a gear transmission. The spindle is concentrically disposed within a spindle nut and operatively connected thereto via a screw thread. The rod drive is disposed coaxially with the spindle and actuatable thereby via an axial bearing.
In accordance with yet another feature of the invention, the sheet-aligning device further includes a front lay shaft connected to the front lays and serving for pivoting the front lays. The spindle nut is axially and radially mounted on the front lay shaft, and a torque support is provided for securing the spindle nut against rotation.
In accordance with a concomitant feature of the invention, the sheet-aligning device further includes a prestressed compression spring operatively supported at one end thereof on the push rod and, at the other end thereof, on the front lay shaft, for restoring the push rod and the combination of the respective front and top lays.
The invention advantageously makes possible combined front and top lays and, nevertheless, also permits vertical adjustability of the top lays. Heretofore, when a combination of the front and top lays was formed, which is a construction that is desirable from structural and drive aspects, vertical adjustment was not possible.
According to a preferred embodiment of the invention, the push rod disposed vertically or nearly vertically, i.e., at least approximately vertically, engages at the upper end thereof with the top lay via a screw connection and, at the lower end thereof, is operatively connected via a sliding piece to a wedge-like slide that is displaceable horizontally or substantially horizontally, i.e., at least approximately horizontally. In this case, the sliding piece should be firmly connected to the push rod by anchoring the lower end of the push rod in a recess formed in the sliding piece.
In order to effect the actuation of the wedge-like slide according to the invention with less expenditure in technical and financial terms, while at the same time being effective and reliable, an advantageous development of the invention proposes that the wedge-like slide be connected to a spindle drive which is actuatable by a motor via a rod drive that is disposed horizontally or nearly horizontally, i.e., at least approximately horizontally.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for aligning sheets on a feeder of a sheet-processing machine, especially a printing press, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.